/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package fi.kinetik.android.currencies.util;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.text.TextUtils;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

/**
 * This class is from Google IOSched project.
 * - added whereEq -method
 * 
 * Helper for building selection clauses for {@link SQLiteDatabase}. Each
 * appended clause is combined using {@code AND}. This class is <em>not</em>
 * thread safe.
 */
public class SelectionBuilder {

    private String mTable = null;

    private Map<String, String> mProjectionMap = new HashMap<String, String>();

    private StringBuilder mSelection = new StringBuilder();

    private ArrayList<String> mSelectionArgs = new ArrayList<String>();

    /**
     * Reset any internal state, allowing this builder to be recycled.
     */
    public SelectionBuilder reset() {
	mTable = null;
	mSelection.setLength(0);
	mSelectionArgs.clear();
	return this;
    }

    /**
     * Builds a simple equals selection of given selection expression.
     *
     * @param selection
     * @param value
     * @return
     */
    public SelectionBuilder whereEq(String selection, String value) {

	return where(selection + "=?", value);

    }

    /**
     * Append the given selection clause to the internal state. Each clause is
     * surrounded with parenthesis and combined using {@code AND}.
     */
    public SelectionBuilder where(String selection, String... selectionArgs) {
	if (TextUtils.isEmpty(selection)) {
	    if (selectionArgs != null && selectionArgs.length > 0) {
		throw new IllegalArgumentException(
			"Valid selection required when including arguments=");
	    }

	    // Shortcut when clause is empty
	    return this;
	}

	if (mSelection.length() > 0) {
	    mSelection.append(" AND ");
	}

	mSelection.append("(").append(selection).append(")");
	if (selectionArgs != null) {
	    for (String arg : selectionArgs) {
		mSelectionArgs.add(arg);
	    }
	}

	return this;
    }

    public SelectionBuilder table(String table) {
	mTable = table;
	return this;
    }

    private void assertTable() {
	if (mTable == null) {
	    throw new IllegalStateException("Table not specified");
	}
    }

    public SelectionBuilder mapToTable(String column, String table) {
	mProjectionMap.put(column, table + "." + column);
	return this;
    }

    public SelectionBuilder map(String fromColumn, String toClause) {
	mProjectionMap.put(fromColumn, toClause + " AS " + fromColumn);
	return this;
    }

    public static String qualified(String column, String table) {
	return table + "." + column;
    }

    /**
     * Return selection string for current internal state.
     *
     * @see #getSelectionArgs()
     */
    public String getSelection() {
	return mSelection.toString();
    }

    /**
     * Return selection arguments for current internal state.
     *
     * @see #getSelection()
     */
    public String[] getSelectionArgs() {
	return mSelectionArgs.toArray(new String[mSelectionArgs.size()]);
    }

    private void mapColumns(String[] columns) {
	for (int i = 0; i < columns.length; i++) {
	    final String target = mProjectionMap.get(columns[i]);
	    if (target != null) {
		columns[i] = target;
	    }
	}
    }

    @Override
    public String toString() {
	return "SelectionBuilder[table=" + mTable + ", selection=" + getSelection()
		+ ", selectionArgs=" + Arrays.toString(getSelectionArgs()) + "]";
    }

    /**
     * Execute query using the current internal state as {@code WHERE} clause.
     */
    public Cursor query(SQLiteDatabase db, String[] columns, String orderBy) {
	return query(db, columns, null, null, orderBy, null);
    }

    /**
     * Execute query using the current internal state as {@code WHERE} clause.
     */
    public Cursor query(SQLiteDatabase db, String[] columns, String groupBy,
	    String having, String orderBy, String limit) {
	assertTable();
	if (columns != null) {
	    mapColumns(columns);
	}
	return db.query(mTable, columns, getSelection(), getSelectionArgs(),
		groupBy, having,
		orderBy, limit);
    }

    /**
     * Execute update using the current internal state as {@code WHERE} clause.
     */
    public int update(SQLiteDatabase db, ContentValues values) {
	assertTable();
	return db.update(mTable, values, getSelection(), getSelectionArgs());
    }

    /**
     * Execute delete using the current internal state as {@code WHERE} clause.
     */
    public int delete(SQLiteDatabase db) {
	assertTable();
	return db.delete(mTable, getSelection(), getSelectionArgs());
    }

}

